Relationship between apparent optical properties and photosynthetic pigments in the sub-alpine Lake Iseo.

The aim of the present study was the evaluation of methods for estimating the content of bio-physical parameters in lake water on the basis of spectral reflectance measured above water surface, in particular the estimation of chlorophyll-a (chl-a) concentrations. Data sets considered refer to some sampling point located in the sub-alpine meso-eutrophic Lake Iseo, surveyed six times over the period March-July and once in November 1998, as these months were very important for the characterization of the springtime algal bloom, which affect the lake waters yearly. At each point station, limnological observations (chlorophyll, total suspended solids, Secchi disk depth) were conducted simultaneously with optical measurements. The latter consisted of water leaving radiance measured by means of a spectroradiometer above the water surface; moreover, a standard reflector radiance was also measured to obtain the water reflectance. Reflectance spectra were transformed according to two well-documented models and correlated to water quality parameters, to investigate their performances as retrieval algorithms under different conditions and referring to different analytical methods. Results outline the sensitivity of the models to chl-a concentrations, different phytoplankton composition, and the sampling depth.

[Drepanocytosis in patients undergoing heart surgery. Anesthesiologic problems]. / Drepanocitosi in pazienti sottoposti a chirurgia cardiaca. Problematiche anestesiologiche.

The authors report their experience with the management of patients with sickle cell trait undergoing open heart surgery. They focus their attention mainly on those factors potentially able to precipitate episodes of sickling, i.e. hypoxia, hypothermia, vascular stasis and acidosis.

[Comparison between propofol and isoflurane in patients undergoing aorto-coronary bypass. Effect on systemic and coronary circulation]. / Confronto tra propofol e isoflurano in pazienti sottoposti ad intervento di bypass aorto-coronarico. Effetti sul circolo sistemico e coronarico.

The Authors report their experience with the use of two different anaesthetic techniques (propofol-fentanil versus isoflurane-fentanyl) for induction and maintenance of anaesthesia in patients undergoing coronary artery surgery. Haemodynamic data (regarding systemic and coronary circulation) showed an almost similar pattern of change after induction, intubation, skin incision and sterotomy, except for a greater decrease of systemic vascular resistances after induction in patients who received propofol. Cardiac output decreased more in the isoflurane group while changes in coronary sinus flow were equal in the two groups.

[Role of creatine phosphate in myocardial protection in heart surgery]. / Ruolo del creatinfosfato (CP) nella protezione miocardica in cardiochirurgia.

The Authors report their experience with the use of Creatine Phosphate (CP) in cardiac surgery. Forty patients undergoing mitral valve replacement are randomly divided into two groups: the former is treated with plain cardioplegia, the latter with CP-enriched cardioplegia at a concentration of 10 mmol/l. A sample of papillary muscle, obtained from the removed valve, is studied by means of spectrophotometric analysis in order to assess the enzyme activities and the intermediate metabolites of the different biochemical pathways of the myocardial cell. Our results suggest a possible interaction of exogenous CP with the cellular metabolism: all the mechanisms involved with the production of energy seem to be shifted towards a better preservation of the available pool of high-energy compounds.